Slide fasteners are widespread as an opening and closing device for daily necessities such as clothing, bags, shoes and general merchandise, but apart from that, are also used in protective clothing such as space suits, chemical protective clothing, diving suits and survival suits, covers for transportation containers and tents. For such special uses, waterproofing property is required even for the slide fasteners.
Generally, a slide fastener is mainly composed of three parts: a pair of long fastener tapes, fastener elements sewn along one side edge of each tape, which are engaging parts of the fastener, and a slider to control opening and closing of the fastener by engaging and separating the fastener elements. Heretofore, there has been known a slide fastener in which a waterproof synthetic resin film is laminated to the fastener tapes for imparting waterproof property, and the synthetic resin films on the bilateral fastener tapes are brought into close contact with each other to exert waterproof property during engagement.
Japanese Patent Laid-Open No. 2000-312604, for example, describes that a laminated synthetic resin film composed of a low melting point-resin layer and a high melting point-resin layer is welded to at least one surface of the fastener tape in the slide fastener in a way that the low melting point-resin layer is in face-to-face contact with the fastener tape surface. As the materials for the laminated synthetic resin film, a urethane-based resin and a polyester-based resin are disclosed.